Conventionally, there is known a processing (referred to as a corresponding point detection processing) for setting, as a target, a stereo image obtained by photographing the same subject from different viewpoints by means of a stereo camera, thereby detecting a pixel capturing the same portion of the subject. There is also known a technique for setting, as a target, each stereo image capturing a sequential change in a subject, thereby detecting a corresponding point (for example, Japanese Patent Application Laid-Open No. 2004-301607 or the like).